.back{
    width: 100%;
    height: 44px;
    line-height: 44px;
    background: #FFFFFF;
    position: relative;
    text-align: center;
    
}
.click-back{
    position: absolute;
    width: 20px;
    height: 20px;
    top: 12px;
    left: 12px;
    background-image: url(./asserts/back.png);
    background-size: cover;
}